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排序方式: 共有53条查询结果,搜索用时 15 毫秒
1.
This paper proposes a new approach based on combined Wavelet Transform-Extreme Learning Machine (WT-ELM) technique for fault section identification (whether the fault is before or after the series capacitor as observed from the relay point), classification and location in a series compensated transmission line. This method uses the samples of fault currents for half cycle duration from the inception of fault. The features of fault currents are extracted by first level decomposition of the current samples using discrete wavelet transform (DWT) and the extracted features are applied as inputs to ELMs for fault section identification, classification and location. The feasibility of the proposed method has been tested on a 400 kV, 300 km series compensated transmission line for all the ten types of faults using MATLAB simulink. On testing 28,800 fault cases with varying fault resistance, fault inception angle, fault distance, load angle, percentage compensation level and source impedance, the performance of the proposed method has been found to be quite promising. The results also indicate that the proposed method is robust to wide variation in system and operating conditions.  相似文献   
2.
Image denoising is a procedure aimed at removing noise from images while retaining as many important signal features as possible. Many images suffer from poor contrast due to inadequate illumination or finite sensitivity of the imaging device, electronic sensor noise or atmospheric disturbances. This paper proposes a hybrid directional lifting technique for image denoising to retain the original information present in the images. The primary objective of this paper is to show the impact of applying preprocessing techniques for improving classification accuracy. In order to classify the image accurately, effective preservation of edges and contour details of an image is essential. The discrete wavelet transform-based interpolation technique is developed for resolution enhancement. The image is then classified using support vector machine classifier, which is well suitable for image classification. The efficiency of the classifier is analyzed based on receiver operating characteristic (ROC) curves. The quantitative performance measures peak signal to noise ratio and ROC analysis show the significance of the proposed techniques.  相似文献   
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On the evaluation of correction terms in Gauss-Legendre quadrature   总被引:1,自引:0,他引:1  
In the numerical integration of analytic functions, the singularities of the integrand affect the rate of convergence of the quadrature. This convergence can be improved significantly by adding the residue correction terms for the poles of the integrand. But this needs the evaluation of the basis function and its corresponding second kind function with complex arguments. We indicate a simple and accurate method to evaluate the correction term involving the basis and its second kind functions in the case of Gauss-Legendre quadrature. This approach does not call for the evaluation of the hypergeometric functions.  相似文献   
5.
The popularity of coffee as a beverage is ever increasing despite the fact that there are reports antagonized to its consumption. Of the several factors cited, the alkaloid caffeine present in coffee can cause addiction and stimulate the central nervous system. It has an effect on the cardiovascular system with a slight increase in blood pressure and heart output. It undergoes biotransformation in the human body to form methylated derivatives of uric acid. In recent times, much effort has gone into the research on the removal of caffeine in coffee, resulting in a specialty product called decaffeinated coffee. Decaffeination methods mainly employ organic solvents or water or supercritical carbon dioxide. These methods with their attendant advantages and disadvantages are reviewed in this article.  相似文献   
6.
K. Ramar  B. Ramaswami 《Automatica》1972,8(6):783-791
A method of designing optimal dynamic compensators for a multi-input multi-output system with polynomial types of desired outputs assuming that the outputs alone are available for feedback is presented in this paper. A performance index quadratic in the state-variable vector, x and a certain derivative of the input to the plant, u is chosen as the criterion for optimality. The problem is solved by first augmenting the plant by a ‘pr’th order compensator and then reducing the augmented system to a regulator system.  相似文献   
7.
OBJECTIVE: With reference to an epidemiological sample of adolescents and young adults the impact of different models on the number of children classified as having specific spelling problems is investigated. METHOD: Using the same set of data, the effect of alternative definitions and methodological procedures on the prevalence of specific spelling retardation is shown. The virtual consequences of various norm-orientated definitions of cases is discussed with reference to external empirical criteria. RESULTS: Particularly, obsolete norms lead to a large overestimation of cases. In the present study case definitions of specific spelling retardation based on substantial criteria result in prevalence rates between 6 and 9 percent. Academic achievement is considerably affected by persisting specific spelling problems and the attendance of secondary schools is rare, in spite of sufficient nonverbal intelligence. CONCLUSIONS: Because of the high impact of spelling ability for educational success, dyslexic children need help by early intervention. Furthermore scholastic promotion is necessary to enable a school carer appropriate to the intellectual possibilities of the child.  相似文献   
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With the advancement in wireless technology and portable devices, smart phones have become one of the belongings of human being. People share their data online, but it has limitations due to transmission range and mobility. Yet opportunistic mobile social network enables users to share data online even if there is no connected path between source and destination. The widespread use of mobile phones equipped with WiFi, Bluetooth, and several other components and contact opportunities among humans bridge the gap between internet available and nonavailable area. In this paper, we have proposed a new routing approach which utilizes both spatial and temporal attributes of user such as probability to meet a particular location and remaining intercontact time between two nodes to select better relay nodes. Generally, users visit different locations such as sports stadium and mall, with varying probability. Users with similar interest form group, and each user has different intercontact time with other users according to their point of interest and visiting pattern. By utilizing multiattributes, different forwarding strategies have been devised for both inter and intragroup routing. The proposed work “point of interest (PoI)‐based routing” is implemented in Opportunistic Network Environment simulator, and the performance is analysed in terms of delivery rate, latency, overhead, goodput, and energy consumed. The simulation results show that PoI diminishes 23% of overhead and yields 24% improvement in goodput over the state‐of‐the‐art protocol. Thus, the simulation results reveal that our proposed work provides the balance between routing performance and resource consumption.  相似文献   
10.
Developing materials with the capability of changing their innate features can help to unravel direct interactions between cells and ligand-displaying features. This study demonstrates the grafting of magnetic nanohelices displaying cell-adhesive Arg-Gly-Asp (RGD) ligand partly to a material surface. These enable nanoscale control of rapid winding (“W”) and unwinding (“UW”) of their nongrafted portion, such as directional changes in nanohelix unwinding (lower, middle, and upper directions) by changing the position of a permanent magnet while keeping the ligand-conjugated nanohelix surface area constant. The unwinding (“UW”) setting cytocompatibility facilitates direct integrin recruitment onto the ligand-conjugated nanohelix to mediate the development of paxillin adhesion assemblies of macrophages that stimulate M2 polarization using glass and silicon substrates for in vitro and in vivo settings, respectively, at a single cell level. Real time and in vivo imaging are demonstrated that nanohelices exhibit reversible unwinding, winding, and unwinding settings, which modulate time-resolved adhesion and polarization of macrophages. It is envisaged that this remote, reversible, and cytocompatible control can help to elucidate molecular-level cell–material interactions that modulate regenerative/anti-inflammatory immune responses to implants.  相似文献   
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